Leonard Joseph Tristano (March 19, 1919 – November 18, 1978) was a jazz pianist, composer, arranger and teacher of jazz improvisation. He performed in the cool jazz, bebop, post bop and avant-garde jazz genres. Historically important are the first recorded free group improvisations ("Intuition"), his preoccupation with atonality and Bach's counterpoint, as well as his early experimentations with recording techniques such as overdubbing (his own playing). In addition, his work as a jazz educator meant that he has exerted a substantial influence on jazz through figures such as Lee Konitz and Warne Marsh.